The overall objectives of this proposal are to 1) determine the mechanisms which following a meal increase blood flow to the digestive organs, maintain flow unchanged in the heart and kidney while reducing flow to skin and muscle; and 2) elucidate the participation of nerves (enteric and somatic) and gastrointestinal hormones in the control of these responses. These studies will be done in conscious and anesthetized dogs. The proposed work is as follows: 1) We will measure simultaneously the blood flow through the celiac, superior mesenteric, inferior mesenteric and either the renal, femoral or coronary artery with flowmeters in conscious dogs following a meal. 2) We will measure simultaneously blood flow from three intestinal segments following placement of foodstuff into the lumen. 3) The participation of nerves in these studies will be determined utilizing nerve section and neural blocking drugs. 4) We will test for changes in vasoactivity of the total venous outflow from the splanchnic viscera during digestion by pumping some of this blood through various organs. Blood from segments of the intestine containing foodstuffs will be similarly tested. 5) We will determine the effects of intravascular infusion of gastrointestinal hormones and end products of digestion of food on various vascular beds to test the possibility that these substances are involved in the observed vascular responses.